Secondary battery and electrical device

Abstract

A secondary battery and an electrical device, the secondary battery comprising: a pouch package (10), an electrode assembly (20), and tabs (30), wherein the pouch package (10) comprises a main body portion (11), a first sealing portion (12), and a second sealing portion (13); the electrode assembly (20) is arranged in the main body portion (11); the main body portion (11) comprises a first wall (113) and a second wall (114); the first wall (113) and the second wall (114) are arranged at an angle; the first sealing portion (12) is connected to the first wall (113), and the second sealing portion (13) is connected to the second wall (114); and a gap is formed between the second sealing portion (13) and the first sealing portion (12) in a second direction (Y). Each tab (30) comprises a tab adhesive (32), and the tab adhesive (32) comprises a tab adhesive main body and an extended portion (322) integrally connected to the tab adhesive main body. The tab adhesive main body is adhered to the pouch package (10), and the projection of the extended portion (322), when viewed in a third direction (Z), falls within the gap. The distance D1 between the extended portion (322) and the second sealing portion (13) in the second direction (Y) satisfies: 0.5mm≤D1≤3mm. In this way, the safety and reliability of the secondary battery can be improved.

Description

Secondary battery and electrical device Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a secondary battery and an electrical device. Background Art

[0002] When packaging the tabs, the tab glue will squeeze to at least one side, and the excess tab glue will overflow the packaging area and squeeze into the packaging area near the adjacent side seal. After curing, the excess tab glue will form a large glue block. In the subsequent folding and sealing process, the glue block is likely to interfere with the folded side seal. Because the glue block is harder than the packaging bag, the side seal adjacent to the glue block can be easily scratched by the glue block under the action of external forces, causing damage to the battery, which in turn affects the safety and reliability of the secondary battery.

[0003] Application Contents

[0004] The purpose of the present application is to provide a secondary battery and an electrical device, aiming to improve the interference between the overflowing glue block and its adjacent and folded side sealing portion, thereby improving the safety and reliability of the secondary battery.

[0005] According to the first aspect of the present application, a secondary battery is provided, comprising a packaging bag, an electrode assembly and a tab. The packaging bag comprises a main body, a first sealing portion and a second sealing portion. The electrode assembly is arranged in the main body. The main body comprises a first wall and a second wall. The first wall is connected to the second wall. The first sealing portion is connected to the first wall, and the second sealing portion is connected to the second wall. Along the second direction, a gap is formed between the second sealing portion and the first sealing portion. The tab comprises a tab glue, and the tab glue comprises a tab glue main body and a protruding portion integrally connected to the tab glue main body. The tab glue main body is adhered to the packaging bag, and the protruding portion protrudes beyond the packaging bag along a third direction. When viewed along the third direction, the projection of the protruding portion falls within the gap. In the thickness direction of the electrode assembly, the third direction, the second direction and the first direction are perpendicular to each other. Along the second direction, the spacing D1 between the protruding portion and the second sealing portion satisfies the following conditions: 0.5mm≤D1≤3mm.

[0006] In the secondary battery involved in this application, limiting D1 to this size range can not only reduce the interference between the overflowing glue block and the second sealing part to improve the safety and reliability of the secondary battery, but also reduce size redundancy, thereby improving the energy density of the secondary battery.

[0007] In one or more optional embodiments above, 0.8 mm ≤ D1 ≤ 2 mm. By regulating D1 within this size range, the safety and reliability of the secondary battery are improved, and its size redundancy is reasonably controlled, thereby further improving the energy density of the secondary battery.

[0008] In one or more optional embodiments above, 0.8 mm ≤ D1 ≤ 1 mm. By regulating D1 within this size range, the safety and reliability of the secondary battery are optimized, and its size redundancy is more reasonably controlled, thereby maximizing the energy density of the secondary battery.

[0009] In one or more optional embodiments above, the first sealing portion is bent toward a first direction, and the second sealing portion is bent toward the first direction, where the first direction is a thickness direction of the electrode assembly.

[0010] In one or more of the above optional embodiments, the main body includes a third wall, the third wall being connected to the first wall and the second wall respectively. The packaging bag includes a third sealing portion, the third sealing portion being connected to the third wall. The tab glue main body is bonded to the third sealing portion, and the protruding portion extends beyond the third sealing portion in the third direction, away from an edge of a side of the third wall.

[0011] In one or more of the above optional embodiments, the third wall includes a first connecting wall and a second connecting wall. The first connecting wall integrally connects the first wall and the second connecting wall, and the first connecting wall is recessed relative to the second wall in the second direction. The second wall is integrally connected to the first connecting wall via the second connecting wall, and the second connecting wall is recessed relative to the first wall in the third direction. The third sealing portion integrally connects the first connecting wall, the second connecting wall, the second sealing portion, and the first sealing portion.

[0012] In one or more of the above optional embodiments, along the third direction, the edge of the third sealing portion away from the third wall does not extend beyond the first wall. This arrangement can shorten the length of the extending portion extending beyond the gap, thereby improving the space utilization of the secondary battery.

[0013] In one or more of the above optional embodiments, along the second direction, a distance D2 between the protruding portion and the first sealing portion satisfies the following: 0.3 mm ≤ D2 ≤ 2.5 mm. Limiting D2 to this size range not only provides a sufficient area for excess glue to be accommodated after the tab body is encapsulated, but also reduces interference between excess glue and the first sealing portion, thereby minimizing energy density loss in the secondary battery.

[0014] In one or more of the above optional embodiments, 0.6 mm ≤ D2 ≤ 1.8 mm.

[0015] In one or more optional embodiments above, D1≥D2. Thus, the location of the tab at the third sealing portion is more reasonable, further reducing design redundancy while further improving the drop resistance performance of the secondary battery.

[0016] In one or more optional embodiments above, the packaging bag has a first cavity and a second cavity connected to the first cavity. The electrode assembly includes an electrode assembly body and a protrusion integrally connected to the electrode assembly body, the electrode assembly body is accommodated in the first cavity, and the protrusion is accommodated in the second cavity. One end of the tab is electrically connected to the electrode assembly body. The electrode assembly includes a plurality of pole pieces and a plurality of isolation membranes. The pole piece includes a pole piece body and a first protrusion integrally connected to the pole piece body. The isolation membrane includes an isolation membrane body and a second protrusion integrally connected to the isolation membrane body. The electrode assembly body is formed by stacking a plurality of pole piece bodies and a plurality of isolation membrane bodies, and the protrusion is formed by stacking a first protrusion and a second protrusion.

[0017] In one or more of the above optional embodiments, the tab comprises a metal strip within the main body, one end of the metal strip being electrically connected to the electrode assembly, and the other end of the metal strip extending out of the packaging bag through the gap. Along the second direction, a distance D3 between a side edge of the metal strip and the protruding portion satisfies the following conditions: 0.8 mm ≤ D3 ≤ 2.5 mm.

[0018] In one or more optional embodiments above, an empty foil area is provided at one corner of the pole piece, and a notch is provided at another corner of the pole piece. The notch is used to avoid the empty foil area of ​​the adjacent pole piece. Along the second direction, the protrusion is provided between the notch and the empty foil area.

[0019] In one or more of the above optional embodiments, the tab comprises a metal strip within the main body, one end of the metal strip being electrically connected to the electrode assembly, and the other end of the metal strip extending out of the packaging bag through the gap. Along the second direction, a distance D4 between the other edge of the metal strip and the protruding portion satisfies the following conditions: 0.8 mm ≤ D4 ≤ 2.5 mm.

[0020] According to a second aspect of the present application, there is provided an electrical device comprising the aforementioned secondary battery.

[0021] Additional aspects and advantages of the embodiments of the present application will be described, shown, or explained in part in the following description through implementation of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] To more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0023] FIG1 is a schematic structural diagram of a secondary battery provided in one embodiment of the present application;

[0024] FIG2 is a schematic structural diagram of another secondary battery provided by one embodiment of the present application;

[0025] FIG3 is an exploded view of the structure of the secondary battery shown in FIG2 ;

[0026] FIG4 is a schematic structural diagram of one electrode piece of the electrode assembly in the secondary battery shown in FIG3 ;

[0027] FIG5 is a partial enlarged view of the secondary battery shown in FIG2 at another angle.

[0028] 10. Packaging bag; 11. Main body; 111. First main wall; 112. Second main wall; 113. First wall; 114. Second wall; 115. Third wall; 1151. First connecting wall; 1152. Second connecting wall; 116. Fourth wall; 117. Fifth wall; 12. First sealing portion; 13. Second sealing portion; 14. Third sealing portion;

[0029] 20, electrode assembly; 201, electrode assembly body; 202, protrusion; 2011, electrode body; 2012, first protrusion; 20111, empty foil area; 2011a, notch;

[0030] 30. Tab; 31. Metal strip; 32. Tab glue; 322. Protruding portion;

[0031] X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0033] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0034] In the description of this application, it should be noted that, unless otherwise specified or limited, the terms "mounted" and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0035] The term "perpendicular" is used to describe the ideal state between two components. In actual production or use, there may be a state that is approximately perpendicular between the two components. For example, combined with numerical descriptions, perpendicular can refer to the angle between two straight lines being in the range of 90°±10°, perpendicular can also refer to the dihedral angle between two planes being in the range of 90°±10°, and perpendicular can also refer to the angle between a straight line and a plane being in the range of 90°±10°. The two components described as "perpendicular" may not be absolute straight lines or planes, but may be roughly straight lines or planes. From a macroscopic perspective, a component can be considered a "straight line" or a "plane" if the overall extension direction is a straight line or a plane.

[0036] The term "parallel" is used to describe an ideal relationship between two components. In actual production or use, two components may be approximately parallel. For example, in conjunction with numerical descriptions, parallel can refer to the angle between two lines being within 180°±10°, the dihedral angle between two planes being within 180°±10°, or the angle between a line and a plane being within 180°±10°.

[0037] Two components described as "parallel" don't necessarily need to be perfectly straight or flat; they can be roughly straight or flat. From a macroscopic perspective, a component is considered "straight" or "flat" if its overall extension is straight or flat. Due to manufacturing tolerances, two planes within 0.5mm of each other are considered parallel.

[0038] The technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0039] As shown in FIG. 1 to FIG. 5 , for ease of description, a three-dimensional rectangular coordinate system is established with the thickness direction of the secondary battery as the first direction X, the width direction of the secondary battery as the second direction Y, and the length direction of the secondary battery as the third direction Z.

[0040] In some embodiments, the first direction X is parallel to the direction in which the first main wall and the second main wall of the packaging bag are relatively arranged as will be described below; in addition, the first direction X is also parallel to the direction in which the pole pieces in the electrode assembly are stacked as will be described below.

[0041] In some embodiments, the second direction Y is parallel to the relative directions of the second wall and the fifth wall in the packaging bag described below; in addition, the second direction Y is also parallel to the opposite side edges of the metal strip described below.

[0042] In some embodiments, the third direction Z is parallel to the relative direction of the first wall and the fourth wall in the packaging bag to be described below; in addition, the third direction Z is also parallel to the extension direction of the tab to be described below.

[0043] First embodiment

[0044] Figure 1 is a schematic diagram of the structure of a secondary battery provided in one embodiment of the present application. As shown in Figure 1 , the secondary battery includes a packaging bag (not shown), an electrode assembly 20, and a tab 30. The electrode assembly 20 is disposed within the packaging bag. One end of the tab 30 is electrically connected to the electrode assembly 20 within the packaging bag, and the other end of the tab 30 extends outside the packaging bag. The portion of the tab 30 extending outside the packaging bag is configured to electrically connect to an electronic device.

[0045] Next, the structure of a soft-pack lithium-ion secondary battery will be described using a soft-pack lithium-ion secondary battery as an example. It is understood that the secondary battery may also be other types of soft-pack secondary batteries besides soft-pack lithium-ion secondary batteries. Examples of such soft-pack secondary batteries include soft-pack sodium-ion secondary batteries, solid-state soft-pack secondary batteries, and semi-solid-state soft-pack secondary batteries.

[0046] The packaging bag is generally flat and includes a main body 11 and multiple sealing portions. The main body 11 has a first main wall 111, a second main wall 112, and a peripheral wall (not shown). The peripheral wall extends between the first main wall 111 and the second main wall 112 and is connected to the first main wall 111 and the second main wall 112. The first main wall 111, the second main wall 112, and the peripheral wall define a receiving cavity for accommodating the electrode assembly 20. The multiple sealing portions are integrally connected to the peripheral wall on all sides, thereby forming a closed container to encapsulate the electrode assembly 20.

[0047] Specifically, the peripheral wall includes a first wall 113 , a second wall 114 and a third wall 115 . The first wall 113 is connected to the second wall 114 through the third wall 115 , and the first wall 113 and the second wall 114 are arranged at an angle.

[0048] The plurality of sealing portions include a first sealing portion 12 and a second sealing portion 13 . The first sealing portion 12 extends outward from the first wall 113 and bends in the first direction X. The second sealing portion 13 extends outward from the second wall 114 and bends in the first direction X.

[0049] Along the second direction Y, a gap 1 a is formed between the second sealing portion 13 and the first sealing portion 12 . The gap 1 a is configured to allow the tab 30 to pass through and extend out of the packaging bag.

[0050] Continuing with FIG. 1 , in some embodiments, the packaging bag can have a flat rectangular shape, with the first and second main walls 111, 112 being substantially flat and parallel to each other, each having the same dimensions and substantially rectangular shape. The peripheral wall can be considered to be four consecutive walls connected in sequence, i.e., the peripheral wall includes not only the first wall 113, the second wall 114, and the third wall 115, but also the fourth wall 116 and the fifth wall 117. The first wall 113, the third wall 115, the second wall 114, the fourth wall 116, and the fifth wall 117 are connected end-to-end in a clockwise direction and are integrally connected to the perimeters of the first and second main walls 111, 112, respectively. In this flat rectangular configuration, the first and second main walls 111, 112 are disposed opposite each other along a first direction X, the second wall 114 and the fifth wall 117 are disposed opposite each other along a second direction Y, and the first and fourth walls 113, 116 are disposed opposite each other along a third direction Z.

[0051] As can be seen from FIG1 , in some embodiments, the first wall 113 and the third wall 115 are different portions of the peripheral wall extending along the second direction Y. When viewed along the third direction Z, the first wall 113 is at least partially obscured by the first sealing portion 12 , while the third wall 115 is exposed in the gap 1 a .

[0052] It is understood that the shape of the packaging bag is not limited to this and can be adapted to actual usage requirements. For example, in alternative embodiments, the packaging bag can be circular, oval, or rectangular with rounded corners. In other words, the first main wall 111 and the second main wall 112 can be circular, oval, or rectangular with rounded corners. In this case, the peripheral wall can be considered a single wall or a plurality of continuous walls connected in sequence.

[0053] In some embodiments, the packaging bag can be made of two independent packaging films (not shown). The two packaging films form a main body portion 11 having the aforementioned accommodating cavity in the middle. The main body portion 11 is sealed and connected around the main body portion 11 to form multiple sealing portions. The first sealing portion 12 and the second sealing portion 13 of the multiple sealing portions are both bent in the first direction X. A recess is punched into one packaging film, and the other packaging film is sealed and connected to the first packaging film around the recess to form multiple sealing portions.

[0054] Alternatively, in some embodiments, the packaging bag may be made of a packaging film, which is folded in half to form two connected parts, a recess is punched out on one part of the packaging film, and then the film is folded in half to seal the recess to form a main body 11 and multiple sealing parts surrounding and connecting the main body 11.

[0055] In the two aforementioned packaging bag configurations, each packaging film includes an outer protective layer (not shown), an inner fusion layer (not shown), and a metal layer (not shown) formed between the outer protective layer and the inner fusion layer. For example, the outer protective layer includes, but is not limited to, nylon, the inner fusion layer includes, but is not limited to, polypropylene, and the metal layer includes, but is not limited to, aluminum foil or steel foil. In the sealing portion, the inner fusion layers of the two packaging films are fused together. Since the inner fusion layer is generally a hot-melt plastic material (polypropylene), the inner fusion layers of the two packaging films can be fused together at the sealing portion by heat pressing.

[0056] The electrode assembly 20 includes a positive electrode sheet (not shown), a negative electrode sheet (not shown), and a separator (not shown) separating the positive electrode sheet and the negative electrode sheet. One of the positive electrode sheet and the negative electrode sheet is electrically connected to the tab 30 .

[0057] The positive electrode sheet includes a positive electrode current collector (not shown) and a positive electrode active material layer (not shown) coated on at least one surface of the positive electrode current collector. The positive electrode current collector is electrically connected to the tab 30 .

[0058] The positive electrode current collector includes, but is not limited to, one or more conductive metal sheets such as aluminum mesh, aluminum foil, copper foil, etc. As an example, the positive electrode current collector is made of aluminum foil.

[0059] The positive electrode active material layer includes, but is not limited to, one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel oxide, lithium manganese iron phosphate, lithium vanadium phosphate, lithium iron phosphate and lithium-rich manganese-based materials.

[0060] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer (not shown) coated on at least one surface of the negative electrode current collector (not shown). The negative electrode current collector is electrically connected to the second electrode tab 30 .

[0061] The negative electrode current collector includes, but is not limited to, one or two of conductive metal sheets such as copper foil and nickel foil. As an example, the negative electrode current collector is made of copper foil.

[0062] The negative electrode active material layer includes, but is not limited to, one or more of artificial graphite, natural graphite, soft carbon, hard carbon, graphene, mesophase carbon microbeads, silicon-based materials, tin-based materials, lithium carbonate, or other metals that can form alloys with lithium.

[0063] As shown in FIG3 , in some embodiments, the electrode assembly 20 may be a laminated structure. Specifically, there are at least two positive electrode sheets and at least two negative electrode sheets, and the at least two positive electrode sheets and the at least two negative electrode sheets are alternately stacked along a first direction X, with a separator separating the positive electrode sheets from the negative electrode sheets.

[0064] Alternatively, the electrode assembly 20 may be a wound structure. Specifically, there is one positive electrode sheet and one negative electrode sheet, and both are in a strip-like structure. The positive electrode sheet, separator, and negative electrode sheet are stacked in sequence and wound two or more times.

[0065] Of course, the electrode assembly 20 may also be other components besides the stacked structure or the wound structure, as long as it can realize the charge and discharge functions of the secondary battery.

[0066] In some embodiments, the secondary battery includes an electrolyte, which is contained in the receiving cavity and permeates the positive electrode sheet, the negative electrode sheet, and the separator.

[0067] Regarding the tab 30, referring to FIG3 in conjunction with FIG2, in some embodiments, the tab 30 includes a metal strip 31 and a tab adhesive 32 disposed around the metal strip 31. The tab adhesive 32 includes a tab adhesive body and a protruding portion 322 integrally connected to the tab adhesive body. The tab adhesive body is adhesively fixed to the third wall 115. The protruding portion 322 extends beyond the third wall 115 along the third direction Z and, when viewed along the third direction Z, the projection of the protruding portion 322 falls within the gap 1a. One end of the metal strip 31 is electrically connected to the electrode assembly 20 within the accommodating cavity, and the other end of the metal strip 31 extends through the gap 1a and out of the packaging bag.

[0068] In some embodiments, the tab 30 can be a positive tab or a negative tab. If the tab 30 is a positive tab, the positive tab is electrically connected to the positive electrode plate. If the tab 30 is a negative tab, the negative tab is electrically connected to the negative electrode plate.

[0069] For ease of explanation, the tab 30 is taken as an example as the positive electrode tab to describe the specific connection method between the tab 30 and the electrode assembly 20.

[0070] It is understandable that the embodiments of the present application do not specifically limit the electrical connection method between the tab 30 and the positive electrode plate.

[0071] For example, the metal strip 31 and the positive electrode current collector are different parts of the same component. In specific implementation, the metal strip 31 and the positive electrode current collector that match the shape of the main body 11 can be die-cut from a complete metal foil, and then a positive electrode active material layer is coated on at least one surface of the positive electrode current collector to form a positive electrode sheet.

[0072] For another example, the tab 30 and the positive electrode current collector are separate components. In a specific implementation, a groove can be scraped out on the positive electrode current collector coated with the positive electrode active material layer to expose the positive electrode current collector surface. The metal strip 31 is then fixed to the positive electrode current collector surface in the groove by, but not limited to, laser welding.

[0073] Continuing to refer to FIG. 3 in conjunction with FIG. 2 , in some embodiments, along the third direction Z, the tab 30 is disposed opposite to the electrical connection points of the plurality of positive electrode sheets and the gap 1 a .

[0074] It is also understood that the structure and shape of the metal strip 31 are not limited in the various embodiments of the present application. For example, the metal strip 31 can be a long strip-shaped structure, and its size can be adaptively set according to actual needs. For example, the width of the metal strip 31 along the second direction Y can be 2mm to 6mm. Preferably, the width of the metal strip 31 along the second direction Y is 2mm to 4mm. The material of the metal strip 31 includes but is not limited to aluminum, nickel, copper, and copper-nickel-plated alloys. For example, when the tab 30 is a positive tab, the material of the metal strip 31 can be aluminum or aluminum-nickel-plated; when the tab 30 is a negative tab, the material of the metal strip 31 can be copper-nickel-plated.

[0075] Please refer back to Figure 1 or refer to Figure 2 and Figure 5. In some embodiments, along the second direction Y, the distance D1 between the protruding portion 322 and the second sealing portion 13 satisfies: 0.5mm≤D1≤3mm. Limiting D1 to this size range can not only reduce the interference between the overflow block and the second sealing portion 13, thereby improving the safety and reliability of the secondary battery; it can also reduce dimensional redundancy, thereby improving the energy density of the secondary battery. This point is described in conjunction with subsequent test results. It should be noted that the distance D1 between the protruding portion 322 and the second sealing portion 13 along the second direction Y mentioned here specifically refers to the distance between the side edge of the protruding portion 322 close to the second sealing portion 13 and the side edge of the second sealing portion 13 close to the protruding portion 322 along the second direction Y, that is, the shortest distance between the protruding portion 322 and the second sealing portion 13.

[0076] Furthermore, 0.8mm≤D1≤2mm. By regulating D1 within this size range, the safety and reliability of the secondary battery are improved, and its dimensional redundancy is reasonably controlled, thereby further improving the energy density of the secondary battery. This can also be illustrated by combining subsequent test results.

[0077] Furthermore, 0.8mm≤D1≤1mm. When D1 is controlled within this size range, the safety and reliability of the secondary battery are optimized, and its dimensional redundancy is more reasonably controlled, thereby maximizing the energy density of the secondary battery. This can also be illustrated by subsequent test results.

[0078] Second embodiment

[0079] In this application, the same reference numerals are used to identify the structural elements with the same names in each embodiment. Based on the description of the above embodiment, the difference is that:

[0080] As shown in Figures 2 and 3, in some embodiments, the packaging bag 10 defines an escape space 1b that communicates with the gap 1a. Specifically, the third wall 115 includes a first connecting wall 1151 and a second connecting wall 1152. The first connecting wall 1151 integrally connects the first wall 113 and the second connecting wall 1152, and the first connecting wall 1151 is recessed relative to the second wall 114 in the second direction Y. The second wall 114 is integrally connected to the first connecting wall 1151 via the second connecting wall 1152, and the second connecting wall 1152 is recessed relative to the first wall 113 in the third direction Z.

[0081] The packaging bag 10 includes a third sealing portion 14 , which is connected to the first connecting wall 1151 and the second connecting wall 1152 respectively and together define the aforementioned escape space 1 b .

[0082] The tab adhesive body is bonded to the third sealing portion 14. The protruding portion 322 extends beyond the third sealing portion 14 along the third direction Z and, when viewed along the third direction Z, the projection of the protruding portion 322 falls within the gap 1a. One end of the metal strap 31 is electrically connected to the electrode assembly 20 within the accommodating cavity, and the other end of the metal strap 31 extends through the gap 1a and out of the packaging bag 10.

[0083] The advantages of adopting the above-mentioned technical solution are: first, hot pressing equipment or tools can be easily inserted into the avoidance space 1b to hot press the tab glue 32 and the third sealing portion 14, thereby improving the manufacturing efficiency of the secondary battery. Second, the connection strength between the tab glue 32 and the third sealing portion 14 depends on the bonding width of the tab glue 32 in the third direction Z. Compared with the bonding width between the tab glue 32 and the third wall 115 along the third direction Z in the first embodiment, the bonding width of the tab glue 32 in the third direction Z in this technical solution is larger, thereby increasing the connection strength between the tab 30 and the packaging bag 10.

[0084] In other embodiments, the third wall 115 extends obliquely relative to the first wall 113 and the second wall 114 , that is, when viewed along the first direction X, an oblique notch is formed between the first wall 113 and the second wall 114 . It should be noted that as long as there is an uneven area of ​​the third wall 115 in the third direction Z, it can be considered that the second top wall is recessed relative to the first top wall in the third direction Z.

[0085] In some embodiments, along the third direction Z, an edge of the third sealing portion 14 away from the second connecting wall 1152 does not extend beyond the first wall 113. This configuration can shorten the length of the protruding portion 322 extending beyond the gap 1a, thereby improving the space utilization of the secondary battery.

[0086] As shown in FIG2 or FIG5 , to improve the sealing effect at the corner between the first wall 113 and the third wall 115, in some embodiments, the edge of the first sealing portion 12 near the tab 30 extends beyond the first connecting wall 1151 along the second direction Y, and the portion of the first sealing portion 12 that extends beyond the first connecting wall 1151 is integrally connected to the third sealing portion 14. In this way, the edge of the first sealing portion 12 near the tab 30 is at a greater distance from both the first wall 113 and the first connecting wall 1151, thereby improving the sealing failure of the packaging bag 10 at the corner between the first wall 113 and the third wall 115, and thus achieving a good sealing effect in the area where the corner is located.

[0087] As can be seen from Figure 2, in some embodiments, along the second direction Y, the distance D2 between the protruding portion 322 and the first sealing portion 12 satisfies the following: 0.3mm≤D2≤2.5mm. If D2 is less than 0.3mm, it means that the distance between the protruding portion 322 and the first sealing portion 12 is too small, which also means that the tab glue body, which is a different part of the same component as the protruding portion 322, is closer to the first connecting wall 1151. This reduces the area of ​​the overflowing glue accommodating area after the tab glue body is packaged, causing the tab glue body to overflow into the folding area of ​​the first sealing portion 12, affecting the subsequent folding of the first sealing portion 12. If D2 is greater than 2.5mm, the design redundancy is too large, and the area of ​​the overflowing glue accommodating area after the tab glue body is packaged is too large, thereby affecting the energy density of the secondary battery. Therefore, limiting D2 to this size range can not only provide sufficient overflowing glue accommodating area for overflowing glue after the tab glue body is packaged, but also reduce the interference between the overflowing glue block and the first sealing portion 12, so as to minimize the energy density loss of the secondary battery. This point will also be explained in conjunction with subsequent test results. It should be noted that the distance D2 between the protruding portion 322 and the first sealing portion 12 along the second direction Y mentioned here specifically refers to the distance between the edge of the protruding portion 322 near the first sealing portion 12 and the edge of the first sealing portion 12 near the tab 30 along the second direction Y, i.e., the shortest distance between the protruding portion 322 and the first sealing portion 12. Preferably, 0.6 mm ≤ D2 ≤ 1.8 mm.

[0088] Furthermore, D1≥D2. As a result, the position of the tab 30 in the third sealing portion 14 is more reasonable, which further reduces design redundancy and further improves the secondary battery's anti-drop performance. This is because D1 is located at the corner of the secondary battery, while D2 is located roughly at the end face of the secondary battery. D1 is larger than D2, which means that D1 has more packaging area, and the buffering effect when falling will be more obvious, thereby further improving the secondary battery's anti-drop performance. Since the third sealing portion 322 will have glue overflow at the packaging during the heat sealing process, the glue overflow direction is the second direction Y, and it is easy to extend a glue block to one side. When the glue overflow block interferes with the folding edge, it will affect the strength of the folding edge. When the third wall 115 is recessed, because the packaging area of ​​the third sealing portion 14 is inside the packaging bag, the glue overflow has little effect on the first sealing portion 12, so D1≥D2 can be achieved.

[0089] As shown in FIG2 or FIG5 , to improve the sealing effect at the corner between the second wall 114 and the third wall 115, in some embodiments, the edge of the second sealing portion 13 near the tab 30 extends beyond the second connecting wall 1152 along the third direction Z, and the portion of the second sealing portion 13 that extends beyond the second connecting wall 1152 is integrally connected to the third sealing portion 14. In this way, the edge of the second sealing portion 13 near the tab 30 is at a greater distance from both the second wall 114 and the second connecting wall 1152, thereby improving the sealing failure of the packaging bag 10 at the corner between the second wall 114 and the third wall 115, and thus achieving a good sealing effect in the area where this corner is located.

[0090] It is worth mentioning that the smaller the area occupied by the avoidance space 1b, the greater the energy density of the secondary battery, and the size of the avoidance space 1b is related to the size of the tab 30. Generally speaking, the specifications of the metal strip 31 are certain, and the area occupied by the avoidance space 1b depends on the width of the tab glue 32 along the second direction Y. The width of the tab glue 32 covering the metal strip 31 in the second direction Y is fixed, and the area occupied by the avoidance space 1b is related to the distance from the metal strip 31 in the second direction Y to the opposite side edges of the protruding portion 322, wherein the width of the protruding portion 322 in the second direction Y is the same as the width of the tab glue body in the second direction Y.

[0091] As shown in Figure 5, in some embodiments, the distance D3 between the metal strip 31 and the edge of one side of the protruding portion 322 along the second direction Y satisfies the following conditions: 0.8mm≤D3≤2.5mm. In this way, the current carrying capacity of the tab 30 can be maintained substantially unchanged while minimizing the area occupied by the avoidance space 1b, thereby further improving the energy density of the secondary battery. Furthermore, 0.8mm≤D3≤1.5mm. It should be noted that the distance between the metal strip 31 and the edge of one side of the protruding portion 322 along the second direction Y mentioned here specifically refers to the distance between the edge of the metal strip 31 facing the protruding portion 322 and the edge of the protruding portion 322 along the second direction Y.

[0092] Similarly, as shown in Figure 5, in some embodiments, the distance D4 between the metal strip 31 and the other side edge of the protruding portion 322 along the second direction Y satisfies the following conditions: 0.8mm≤D4≤2.5mm. In this way, the current carrying capacity of the tab 30 can be maintained substantially unchanged while minimizing the area occupied by the avoidance space 1b, thereby further improving the energy density of the secondary battery. Furthermore, 0.8mm≤D4≤1.5mm. It should be noted that the distance between the metal strip 31 and the other side edge of the protruding portion 322 along the second direction Y mentioned here specifically refers to the distance between the other side edge of the metal strip 31 toward the protruding portion 322 and the other side edge of the protruding portion 322 along the second direction Y.

[0093] As shown in FIG3 , in some embodiments, the accommodating cavity includes a first cavity (not shown) and a second cavity (not shown) communicating with the first cavity. The first cavity can be enclosed by the first wall 113, the first connecting wall 1151, the second connecting wall 1152, and the virtual connection between the second connecting wall 1152 and a portion of the fifth wall 117. The second cavity can be enclosed by the second wall 114, the fourth wall 115, and the virtual connection between the first connecting wall and the remaining portion of the fifth wall 117.

[0094] The electrode assembly 20 includes an electrode assembly body 201 and a protrusion 202 integrally connected to the electrode assembly body 201. The electrode assembly 20 is housed in a first cavity, and the protrusion 202 is housed in a second cavity. Specifically, each electrode includes a electrode body 2011 and a first protrusion 2012 integrally connected to the electrode body 2011, and each isolation membrane 23 includes an isolation membrane body (not shown) and a second protrusion (not shown) integrally connected to the isolation membrane body. The electrode assembly body 201 can be formed by alternatingly stacking at least two electrode body 2011 and at least two isolation membrane bodies along a first direction X. The protrusion 202 can be formed by alternatingly stacking at least a first protrusion 2012 and at least two second protrusions along a first direction X.

[0095] In some embodiments, an empty foil area 20111 is provided at one corner of the pole piece, and a notch 2011a is provided at another corner of the pole piece. The notch 2011a is used to avoid the empty foil area 20111 of the adjacent pole piece. Along the second direction Y, the first protrusion 2012 is provided between the notch 2011a and the empty foil area 20111. As shown in Figure 3, it is an electrode assembly after multiple electrode sheets and diaphragms are stacked. The multiple electrode sheets are divided into positive electrode sheets and negative electrode sheets. One corner of the positive electrode sheet is provided with an empty foil area 20111, and the other corner is provided with a notch 2011a. The negative electrode sheet is provided with an empty foil area 20111 and a notch 2011a at opposite positions. Therefore, the notch 2011a of the positive electrode sheet can avoid the empty foil area 20111 of the adjacent negative electrode sheet, and the notch 2011a of the negative electrode sheet can also avoid the empty foil area 20111 of the adjacent positive electrode sheet. Multiple empty foil areas 20111 are stacked and finally electrically connected to the tab 30.

[0096] It should be noted that the difference between the pole piece body 2011 and the first protrusion 2012 lies in their location, while the rest of their structures are substantially the same. That is, both the pole piece body 2011 and the first protrusion 2012 include a current collector and an active material layer. The difference between the separator body and the second protrusion lies in their location, while the rest of their structures are substantially the same.

[0097] In the first cavity, the electrode assembly body is electrically connected to one end of the metal strip. The metal strip is connected to a corner of the electrode assembly body 201. Specifically, multiple electrode bodies 2011 of the same polarity are electrically connected to one end of the metal strip.

[0098] The present application is further described below with reference to the following examples and comparative examples. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "parts" and "%" are by weight. It should be understood that these examples are intended only to illustrate the present application and are not intended to limit the scope of the present application.

[0099] Secondary battery drop impact + high temperature and high humidity test:

[0100] Fully charge a secondary battery and then drop it from a height of 1.5 meters onto a smooth marble surface. The order of drops is: front-back-bottom-top-left-right-upper-left-right-lower-left-lower-right. Each side or corner is dropped twice in a row, constituting one drop cycle. Each secondary battery undergoes 10 drops in total. After 10 drops, place the battery in a high-temperature (≥60°C) and high-humidity (≥95%) environment for 24 hours. Measure the battery voltage and inspect its appearance. A battery passes the test if it does not become hot, catch fire, explode, leak, or emit smoke.

[0101] Example 1-1

[0102] The positive electrode sheet (80mm×30mm), separator, and negative electrode sheet prepared above are stacked in order, with the separator placed between the positive and negative electrode sheets to act as a separator, and then wound to obtain an electrode assembly. The electrode assembly is placed in the prepared packaging film, dehydrated at 80°C, injected with the prepared electrolyte, and subjected to vacuum packaging, standing, formation, hot pressing and other processes to obtain a secondary battery. Wherein, D1=0.5mm, D2=0.6mm, and gap 1a=6.1mm. Gap 1a is the sum of D1, D2 and D5, D5=5mm, where D5=D3+D4+the width of the metal strip along the second direction.

[0103] Example 1-2

[0104] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 0.6 mm, D5 = 5 mm, and the gap 1a = 6.4 mm.

[0105] Examples 1-3

[0106] The difference from Example 1-1 is that D1 = 1 mm, D2 = 0.6 mm, D5 = 5 mm, and the gap 1a = 6.6 mm.

[0107] Examples 1-4

[0108] The difference from Example 1-1 is that D1 = 1.5 mm, D2 = 0.6 mm, D5 = 5 mm, and the gap 1a = 7.1 mm.

[0109] Examples 1-5

[0110] The difference from Example 1-1 is that D1 = 2 mm, D2 = 0.6 mm, D5 = 5 mm, and the gap 1a = 7.6 mm.

[0111] Examples 1-6

[0112] The difference from Example 1-1 is that D1 = 3 mm, D2 = 0.6 mm, D5 = 5 mm, and the gap 1a = 8.6 mm.

[0113] Comparative Example 1-1

[0114] The difference from Example 1-1 is that D1 = 0.3 mm, D2 = 0.6 mm, D5 = 5 mm, and the gap 1a = 5.9 mm.

[0115] Comparative Example 1-2

[0116] The difference from Example 1-1 is that D1 = 3.5 mm, D2 = 0.6 mm, D5 = 5 mm, and the gap 1a = 9.1 mm.

[0117] Example 2-1

[0118] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 0.2 mm, D5 = 5 mm, and the gap 1a = 6 mm.

[0119] Example 2-2

[0120] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 0.3 mm, D5 = 5 mm, and the gap 1a = 6.1 mm.

[0121] Example 2-3

[0122] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 0.6 mm, D5 = 5 mm, and the gap 1a = 6.4 mm.

[0123] Examples 2-4

[0124] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 1 mm, D5 = 5 mm, and the gap 1a = 6.8 mm.

[0125] Examples 2-5

[0126] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 1.8 mm, D5 = 5 mm, and the gap 1a = 7.6 mm.

[0127] Examples 2-6

[0128] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 2.5 mm, D5 = 5 mm, and the gap 1a = 8.3 mm.

[0129] Examples 2-7

[0130] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 3 mm, D5 = 5 mm, and the gap 1a = 8.8 mm.

[0131] Comparative Example 1

[0132] The difference from Example 1-1 is that D1 = 0.3 mm, D2 = 0.6 mm, D5 = 5 mm, and the gap 1a = 5.9 mm.

[0133] Comparative Example 2

[0134] The difference from Example 1-1 is that D1 = 3.5 mm, D2 = 0.6 mm, D5 = 5 mm, and the gap 1a = 9.1 mm.

[0135] Table 1

[0136] Comparing any one of Examples 1-1 to 1-6 with Comparative Example 1 or Comparative Example 2, it can be seen that D1 satisfies: 0.5mm≤D1≤3mm. Limiting D1 within this size range can not only reduce the interference between the overflowing glue block and the second sealing part, thereby improving the safety and reliability of the secondary battery; but also reduce dimensional redundancy, thereby improving the energy density of the secondary battery.

[0137] Furthermore, 0.8mm≤D1≤2mm. By regulating D1 within this size range, the safety and reliability of the secondary battery are improved, and its dimensional redundancy is reasonably controlled, thereby further improving the energy density of the secondary battery. This can also be illustrated by combining subsequent test results.

[0138] Furthermore, 0.8mm≤D1≤1mm. When D1 is controlled within this size range, the safety and reliability of the secondary battery are optimized, and its size redundancy is more reasonably controlled, thereby maximizing the energy density of the secondary battery.

[0139] Comparing any one of Examples 2-1 to 2-7 with Comparative Example 1, it can be seen that when D1 is within the aforementioned value range and D2 takes any value, the drop+high temperature+high humidity pass rate of the secondary battery is improved compared with the secondary battery in Comparative Example 1.

[0140] Comparing any of Examples 2-2 to 2-6 with Example 2-1 or Example 2-7 shows that 0.3 mm ≤ D2 ≤ 2.5 mm. Adjusting D2 within this size range can reduce the interference between the overflowing glue block and the first sealing portion and minimize the energy density loss of the secondary battery.

[0141] Furthermore, 0.6mm≤D1≤1.8mm. When D1 is controlled within this size range, the safety and reliability of the secondary battery are improved, and its size redundancy is more reasonably controlled, thereby reducing the energy density loss of the secondary battery.

[0142] It can be seen that the secondary battery involved in the embodiment of the present application can improve the interference between the overflowing glue block and the adjacent and folded side sealing portion, thereby improving the safety and reliability of the secondary battery.

[0143] Another embodiment of the present application further provides an electrical device comprising any of the above-mentioned secondary batteries. The electrical device of the present application may be, but is not limited to, a laptop computer, a pen-type computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household battery, and a lithium-ion capacitor, etc.

[0144] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A secondary battery comprising a packaging bag, an electrode assembly, and a tab, wherein the packaging bag comprises a main body, a first sealing portion, and a second sealing portion; the electrode assembly is disposed within the main body; the main body comprises a first wall and a second wall; the first wall is connected to the second wall; the first sealing portion is connected to the first wall; and the second sealing portion is connected to the second wall. Along the second direction, a gap is formed between the second sealing portion and the first sealing portion; The tab includes tab glue, the tab glue includes a tab glue body and a protruding portion integrally connected to the tab glue body, the tab glue body is adhered to the packaging bag, the protruding portion protrudes from the packaging bag along a third direction, and when viewed along the third direction, a projection of the protruding portion falls within the gap, wherein the third direction, the second direction, and the thickness direction of the electrode assembly are perpendicular to each other; Along the second direction, a distance D1 between the protruding portion and the second sealing portion satisfies: 0.5 mm ≤ D1 ≤ 3 mm.

2. The secondary battery according to claim 1, wherein 0.8mm≤D1≤2mm.

3. The secondary battery according to claim 2, wherein 0.8mm≤D1≤1mm.

4. The secondary battery according to claim 1, wherein The first sealing portion is bent toward a first direction, and the second sealing portion is bent toward the first direction. The first direction is a thickness direction of the electrode assembly.

5. The secondary battery according to claim 1, wherein: The main body includes a third wall, and the third wall is connected to the first wall and the second wall respectively; The packaging bag includes a third sealing portion, wherein the third sealing portion is connected to the third wall; The tab glue body is bonded to the third sealing portion, and the protruding portion extends beyond the third sealing portion along the third direction and is away from an edge of one side of the third wall.

6. The secondary battery according to claim 5, characterized in that The third wall includes a first connecting wall and a second connecting wall, wherein the first connecting wall integrally connects the first wall and the second connecting wall, and the first connecting wall is recessed relative to the second wall toward the second direction, the second wall is integrally connected to the first connecting wall via the second connecting wall, and the second connecting wall is recessed relative to the first wall toward the third direction; The third sealing portion integrally connects the first connecting wall, the second connecting wall, the second sealing portion, and the first sealing portion.

7. The secondary battery according to claim 6, characterized in that Along the third direction, an edge of the third sealing portion away from the third wall does not extend beyond the first wall.

8. The secondary battery according to claim 6, wherein An edge of one side of the first sealing portion close to the electrode tab extends beyond the first connecting wall along the second direction.

9. The secondary battery according to claim 6, wherein Along the second direction, a distance D2 between the protruding portion and the first sealing portion satisfies: 0.3 mm ≤ D2 ≤ 2.5 mm.

10. The secondary battery according to claim 9, wherein 0.6mm≤D2≤1.8mm.

11. The secondary battery according to claim 9, wherein D1≥D2.

12. The secondary battery according to any one of claims 11, wherein: The packaging bag has a first cavity and a second cavity communicating with the first cavity; The electrode assembly includes an electrode assembly body and a convex portion integrally connected to the electrode assembly body, the electrode assembly body is accommodated in the first cavity, and the convex portion is accommodated in the second cavity; One end of the tab is electrically connected to the electrode assembly body; The electrode assembly includes a plurality of pole pieces and a plurality of isolation membranes; The pole piece includes a pole piece body and a first protruding portion integrally connected to the pole piece body; The isolation membrane includes an isolation membrane body and a second protruding portion integrally connected to the isolation membrane body; The electrode assembly body is formed by stacking the plurality of electrode sheet bodies and the plurality of isolation membrane bodies, and the protrusion is formed by stacking the first protruding portion and the second protruding portion.

13. The secondary battery according to claim 12, characterized in that An empty foil area is provided at one corner of the pole piece, and a notch is provided at another corner of the pole piece, wherein the notch is used to avoid the empty foil area of the adjacent pole piece; Along the second direction, the first protruding portion is arranged between the notch and the empty foil area.

14. The secondary battery according to any one of claims 1 to 4, characterized in that: The tab comprises a metal strip, which is inside the main body, one end of the metal strip is electrically connected to the electrode assembly, and the other end of the metal strip passes through the gap and extends out of the packaging bag; The secondary battery satisfies at least one of the following conditions: (1) Along the second direction, the distance D3 between the edge of one side of the metal strip and the protruding portion satisfies the following conditions: 0.8 mm ≤ D3 ≤ 2.5 mm; (2) Along the second direction, the distance D4 between the other side edge of the metal strip and the protruding portion satisfies: 0.8 mm ≤ D4 ≤ 2.5 mm.

15. An electrical device, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 14.

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